Characterization and Modeling of Irradiation Induced Nanoclusters in Ferritic-Martensitic and Zirconium-Niobium Alloys.

The objective of this dissertation is to characterize, and model irradiation-induced solute clustering in commercially ferritic-martensitic alloys (T91, HCM12A, and HT9) and Zr-1 % Nb alloys following ions or neutron irradiations and also to prescribe the required temperature shift for ion irradiations to emulate neutron irradiation. Ferritic-martensitic alloys are irradiated with Fe2+ or neutrons to a dose of 3 dpa at 500 °C and 370 °C while Zr- 1 %Nb alloy is irradiated with Kr2+ or neutrons irradiated to 5 dpa at 310 °C. Irradiation induced segregation and nanocluster morphology are analyzed using atom probe tomography. The size and number density in each F/M alloys differ with ions or neutron irradiation while the morphology of Nb-rich nanoclusters following Krypton irradiation is comparable to that seen after neutron irradiation. Two distinct models (Cluster dynamic and NHM model) are utilized to simulate nanocluster evolution in F/M alloys and they both predicted a negative temperature shift will be needed for ion irradiation to emulate neutron irradiation damage.doctoral, Ph.D., Materials Science -- University of Idaho - College of Graduate Studies, 2020-1